Liquid lead-acid battery

Abstract

To provide a liquid type lead storage battery which suppresses an increase in liquid surface level of electrolyte by devices of an irregular part caused by gear seal in the liquid type lead storage battery provided with a bag-shaped separator whose both end parts in a width direction are sealed with the gear seal.SOLUTION: A bag-shaped separator 1 opens only an upper side of cell chambers, has both end parts in the width direction perpendicular to a lamination direction and a vertical direction of a laminate that are closed with a waveform irregular part 11 displaced in the lamination direction Y by following the vertical direction Z, and has a flat part outside in the width direction of the irregular part. A height difference (H) of the irregular part and repeating unit length (wavelength of waveform: W) satisfy the following formula (1) to formula (3): 0.5 mm≤H≤1.0 mm...(1); 1.5 mm≤W≤5.0 mm...(2); and 0.2≤H / W≤0.5...(3).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to flooded lead-acid batteries. [Background technology]

[0002] A typical flooded lead-acid battery includes a battery case having a cell chamber, a plate assembly housed in the cell chamber, an electrolyte injected into the cell chamber, and a lid fixed to the battery case to close the top of the cell chamber. The plate assembly has a stack of alternating positive and negative plates and a separator disposed between the positive and negative plates. The positive plate has a positive current collector with a lattice portion and a positive mixture (a material containing a positive active material) held in the lattice portion. The negative plate has a negative current collector with a lattice portion and a negative mixture (a material containing a negative active material) held in the lattice portion. The stack is disposed in the battery case with the plate surfaces of the positive and negative plates aligned in the vertical direction of the battery case.

[0003] As the separator, a bag-shaped separator made of a synthetic resin (e.g., polyolefin) is used. When a bag-shaped separator is used, the laminate is in a state in which a first electrode plate, which is one of the positive electrode plate and the negative electrode plate, is housed in the bag-shaped separator, and the bag-shaped separator containing the first electrode plate and a second electrode plate, which is the other of the positive electrode plate and the negative electrode plate, are alternately stacked, so that the separator is disposed between the positive electrode plate and the negative electrode plate.

[0004] The pouch-shaped separators that are usually used are those in which only the upper side of the cell chamber is open and both ends in the width direction, which is perpendicular to the stacking direction of the laminate and the up-down direction of the battery case, are closed by gear seals. The pouch-shaped separator obtained by gear sealing has a corrugated uneven portion that continues in the up-down direction of the battery case and displaces in the stacking direction, and has a flat portion (a portion not gear sealed) at the extreme end in the width direction (outside the uneven portion in the width direction).

[0005] A method for obtaining a bag-shaped separator whose both widthwise ends are closed with gear seals is described in, for example, Patent Document 1. In the method described in Patent Document 1, a sheet-shaped separator is folded in half and passed between two meshing gears to join both widthwise ends. The reason for providing a flat portion (a portion not gear-sealed) at the very end in the widthwise direction (outside the uneven portion in the widthwise direction) is that without this flat portion, when the electrode plate group is stored in the cell chamber of the battery case during assembly, the uneven portion of the bag-shaped separator may come into contact with the inner wall of the cell chamber, causing damage or peeling of the uneven portion (gear seal portion).

[0006] When such flooded lead-acid batteries are used as automobile batteries, they are often used in an overcharged state, which tends to increase the amount of gas generated from the plates during charging. If the gas is not discharged outside the battery and remains in the electrolyte, the electrolyte level may rise due to the gas accumulation, and the electrolyte may overflow outside the battery. The overflowing electrolyte may adhere to the terminals, attached frames, earth wires, etc., causing them to corrode and deteriorate. Therefore, it is necessary to prevent the electrolyte level from rising.

[0007] Conventional techniques for preventing electrolyte overflow caused by such a rise in the liquid level include, for example, a method described in Patent Document 2 in which the upper end of a slit provided in a vent plug is set at a high position. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 3637446 [Patent Document 2] JP 2008-71601 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a flooded lead-acid battery having a bag-shaped separator whose both widthwise ends are closed by gear seals, in which a rise in the electrolyte level is suppressed by devising uneven portions created by the gear seal. [Means for solving the problem]

[0010] In order to solve the above problems, a flooded lead-acid battery according to one embodiment of the present invention has the following configurations (a) to (c). (a) A battery case having a cell chamber, a plate group housed in the cell chamber, an electrolyte injected into the cell chamber, and a lid fixed to the battery case to close the upper part of the cell chamber. The plate group has a laminate consisting of a plurality of positive and negative electrode plates, and a bag-shaped separator made of synthetic resin. In the laminate, a first electrode plate, which is one of the positive and negative electrode plates, is housed in the bag-shaped separator, and the bag-shaped separator containing the first electrode plate and a second electrode plate, which is the other of the positive and negative electrode plates, are alternately stacked, and a separator is disposed between the positive and negative electrode plates. The laminate is disposed in the battery case with the plate surfaces of the positive and negative electrode plates aligned along the vertical direction of the battery case.

[0011] (b) the bag-shaped separator is open only at the upper side of the cell chamber, and both ends in a width direction, which is a direction perpendicular to the stacking direction and the up-down direction of the laminate, are closed by a corrugated uneven portion (gear seal portion) that is continuously displaced in the stacking direction in the up-down direction, and has a flat portion on the outer side in the width direction (the outermost end in the width direction) of the uneven portion, (c) The height difference (H) of the concave-convex portion and the repeating unit length (wavelength: W) of the corrugated portion satisfy the following formulas (1) to (3). 0.5mm≦H≦1.0mm (1) 1.5mm≦W≦5.0mm (2) 0.2≦H / W≦0.5 (3) Effect of the Invention

[0012] The flooded lead-acid battery of the present invention is a flooded lead-acid battery having a bag-shaped separator whose both widthwise ends are closed by gear seals, and it is expected that the rise in the electrolyte level will be suppressed by designing the unevenness created by the gear seal. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a front view showing a state in which a first electrode plate is housed in a pouch-shaped separator in a stack constituting the flooded lead-acid battery of the embodiment. [Diagram 2] 2 is a partial view of the AA cross section of FIG. 1, showing a cross section of a gear seal portion of a bag-shaped separator. [Diagram 3] FIG. 13 is a schematic diagram for explaining why a rise in the liquid level of the electrolyte occurs, and is a plan view showing a state in which the stack is housed in a cell chamber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention.

[0015] [Explanation of overall configuration] The flooded lead-acid battery of this embodiment has a monoblock-type battery case, a lid, and six plate groups. The battery case is divided into six cell chambers by partitions. The six cell chambers are arranged along the longitudinal direction of the battery case. Each cell chamber contains one plate group and is filled with an electrolyte. Each plate group has a laminate made of alternating positive and negative plates and separators arranged between the positive and negative plates.

[0016] The positive electrode plate is composed of a positive electrode current collector and a positive electrode mixture (a mixture containing a positive electrode active material), and the positive electrode current collector has a rectangular lattice portion and ears protruding upward from the lattice portion, and the positive electrode mixture is held in the lattice portion. The negative electrode plate is composed of a negative electrode current collector and a negative electrode mixture (a mixture containing a negative electrode active material), and the negative electrode current collector has a rectangular lattice portion and ears protruding upward from the lattice portion, and the negative electrode mixture is held in the lattice portion. The multiple positive and negative electrode plates are arranged alternately with separators between them.

[0017] The positive electrode plate is housed in a pouch-shaped separator. The pouch-shaped separator containing the positive electrode plate and the negative electrode plate are stacked alternately, with the separator disposed between the positive electrode plate and the negative electrode plate. Each plate group has positive and negative straps that connect the positive and negative plates of the stack at different positions in the width direction, and positive and negative intermediate poles that rise from the positive and negative straps, respectively. The positive and negative straps connect the lugs of the positive and negative plates, respectively. The positive and negative straps arranged in the cell chambers at both ends in the cell arrangement direction have positive and negative poles formed thereon via small pieces, which are connected to the positive and negative poles that serve as external terminals.

[0018] [About the bag-shaped separator] As shown in Fig. 1, a positive electrode plate 2 is housed in a bag-shaped separator 1 that constitutes a laminate. Only a portion of the bag-shaped separator 1 that is the upper side of the cell chamber is open, and both ends in a width direction X that is a direction perpendicular to the stacking direction of the laminate (direction perpendicular to the paper surface of Fig. 1) and the vertical direction Z of the battery case are closed by a gear seal. The gear seal forms an uneven portion 11 that is continuous in the vertical direction in the bag-shaped separator 1 slightly toward the center from the end in the width direction. The gear seal is also formed so that a flat portion 12 remains at the end in the width direction.

[0019] A grid portion 21 of the current collector plate constituting the positive electrode plate 2 is disposed inside the bag-shaped separator 1 , and a lug portion 22 protrudes from the opening of the bag-shaped separator 1 . As shown in FIG. 2, the shape of the concave-convex portion 11 is a wave shape that continues in the vertical direction Z and is displaced in the stacking direction Y. The repeating units of the corrugations of the concave-convex portion 11 are present in the range of 3 to 7 per 10 mm in the vertical dimension of the bag-shaped separator 1. In addition, the height difference (H) of the concave-convex portion and the repeating unit length (wavelength: W) satisfy the following formulas (1) to (3). 0.5mm≦H≦1.0mm (1) 1.5mm≦W≦5.0mm (2) 0.2≦H / W≦0.5 (3) Furthermore, the width (dimension in the X direction) of the uneven portion 11 is in the range of 2 mm or more and 5 mm or less, and the width of the flat portion 12 is in the range of 1 mm or more and 5 mm or less.

[0020] [Actions and Effects of the Embodiments] The flooded lead-acid battery of this embodiment has a bag-shaped separator 1 whose both widthwise ends are closed by gear seals. By configuring the unevenness 11 caused by the gear seal as described above, it is possible to suppress a rise in the electrolyte level caused by gas accumulation while ensuring the necessary sealing performance.

[0021] There are two examples of small H / W: when W is the same and H is small, and when H is the same and W is large. As long as H is within the range that satisfies formula (1) and W is within the range that satisfies formula (2), the required sealing performance can be ensured in either case by satisfying 0.2≦H / W. There are two examples of a large H / W ratio: when W is the same and H is large, and when H is the same and W is small. In either case, as long as H is within a range that satisfies formula (1) and W is within a range that satisfies formula (2), the rise in the electrolyte level due to gas accumulation can be suppressed by satisfying H / W≦0.5.

[0022] The larger the H / W, the better the sealing (adhesion) provided by the uneven portion 11 of the bag-shaped separator 1, but the greater the force applied in the thickness direction of the bag-shaped separator 1, making both ends of the bag-shaped separator more likely to bend at the uneven portion 11. As shown in Fig. 3, a battery case 4 equipped with a plurality of cell chambers 40 has a side plate 41 and a partition plate 42, and the cell chamber 40 is formed by an inner surface 41a of the side plate 41 and an inner surface 42a of the partition plate. When a laminate 10 consisting of a bag-shaped separator 1, a positive electrode plate 2, and a negative electrode plate 3 is placed in the cell chamber 40, if the bag-shaped separator 1 is bent at both ends, the area between the bent portion 15 of the bag-shaped separator 1 (the portion consisting of the uneven portion 11 and the flat portion 12) and the inner surface 41a of the side plate 41 of the battery case 4 becomes a portion where gas is likely to remain in the electrolyte. As a result, gas generated during charging remains in this portion and is difficult to be discharged to the outside of the battery, causing the liquid level of the electrolyte to rise.

[0023] In addition, as H / W becomes smaller, the sealing property (adhesion) of the uneven portion 11 of the bag-shaped separator 1 decreases, but since the force applied in the thickness direction of the bag-shaped separator 1 is small, the above-mentioned bending at both ends of the bag-shaped separator is less likely to occur. In addition, if the above-mentioned sealing property decreases, there is a risk that the positive electrode plate will come out of the bag-shaped separator and a short circuit will occur due to contact between the positive electrode plate and the negative electrode plate.

[0024] In addition, in the flooded lead-acid battery of this embodiment, since the positive electrode plate is housed in a pouch-shaped separator, the effect of suppressing the rise in the liquid level caused by gas accumulation is higher than in the case where the negative electrode plate is housed in a pouch-shaped separator. The reasons for this are considered to be as follows. First, gas generated from the electrode plates housed in the bag-shaped separator tends to remain in the bag-shaped separator. During charging, oxygen is generated from the positive electrode plate and hydrogen is generated from the negative electrode plate due to electrolysis of water. The ratio of hydrogen to oxygen generated is "hydrogen:oxygen = 2:1", and the amount of gas generated from the positive electrode plate is less than the amount of gas generated from the negative electrode plate. Therefore, by housing the positive electrode plate in a bag-shaped separator, the rise in the liquid level caused by gas accumulation can be further suppressed.

[0025] 〔others〕 One method for making the W and H of the uneven portion 11 of the bag-shaped separator satisfy 0.2≦H / W≦0.5 is to change the gear seal conditions when joining both widthwise ends of a sheet-shaped separator folded in half with a gear seal so that the required H and W are obtained. That is, in a gear seal, a separator cut from a separator roll is folded and passed between meshing gears rotating at a constant speed in a gear seal device to join both ends of the separator in the width direction, and the gears used have a tooth length (which determines H) and tooth pitch (which determines W) that will give the required H and W. Alternatively, the distance between the meshing gears is set to a value that will give the required H and W.

[0026] The method for storing the positive electrode plate in the bag-shaped separator may be a method in which the positive electrode plate is stored in a bag-shaped separator obtained by gear sealing, or a method in which the positive electrode plate is placed in a folded separator and both ends in the width direction are gear-sealed. In addition, a rib may be formed on the surface of the bag-shaped separator facing the positive electrode plate or the negative electrode plate. From the viewpoint of suppressing oxidative deterioration due to oxygen gas generated from the positive electrode plate, the rib is preferably formed on the positive electrode plate side. In the flooded lead-acid battery of the embodiment, the positive electrode plate is housed in the pouch-shaped separator, but the negative electrode plate may also be housed in the pouch-shaped separator. EXAMPLES

[0027] [Preparation of test battery] As the flooded lead-acid batteries of Samples No. 1 to No. 10, flooded lead-acid batteries of D23 size were fabricated with the same structure as the flooded lead-acid battery of the embodiment. <Preparation of positive and negative electrode plates before chemical formation> First, a positive electrode current collector made of a lead alloy was produced by a book mold casting method. A negative electrode current collector made of a lead alloy was produced by a continuous casting method. Next, a paste of a mixture (positive electrode mixture) containing a positive electrode active material produced by a normal method was filled into the lattice-shaped part of the positive electrode current collector, and the mixture was aged and dried to obtain a positive electrode plate (positive electrode filled plate) before chemical formation. A paste of a mixture (negative electrode mixture) containing a negative electrode active material produced by a normal method was filled into the lattice-shaped part of the negative electrode current collector, and the mixture was aged and dried to obtain a negative electrode plate (negative electrode filled plate) before chemical formation.

[0028] <Preparation of bag-shaped separator> The pouch-shaped separators were made in the following way. First, a porous polyethylene separator with a base thickness of 0.25 mm and a width of 152 mm was prepared in the form of a strip, with 18 ribs, each 0.6 mm wide and 0.65 mm high, formed at 7 mm intervals on one side, wound into a roll (separator roll). Separators cut to lengths of 240 mm from this separator roll were folded over so that the ribs were on the inside or outside, and the edges were gear-sealed to obtain pouch-shaped separators A to G and I to K, each 120 mm in the Z direction and 152 mm in the X direction.

[0029] The uneven portion 11 was formed with a gear seal so that the dimension in the X direction was 3 mm, and the dimension in the X direction of the flat portion 12 was 2 mm. In addition, by performing gear sealing using gears with different tooth lengths and tooth pitches for the gear seal machine, six types of bag-shaped separators with different height differences (H) and repeat unit lengths (wavelength: W) of the uneven portion 11 were produced. The tightening torque of the screws for fitting the gears was the same at 2.5 N m.

[0030] Specifically, pouch-shaped separators A to G and I to K were produced, each having a height difference (H) and repeating unit length (W) as shown in Table 1. These separators satisfy formulas (1) and (2). Table 1 also shows the ratio (H / W) of the height difference (H) to the repeating unit length (W) of each pouch-shaped separator.

[0031] [Table 1]

[0032] <Preparation of electrode plates and subsequent processes> 10 x 6 x 7 positive electrode packed plates and 10 x 6 x 8 negative electrode packed plates were prepared using the method described above. Next, for battery No. 1, seven sheets of the bag-shaped separator A were used, seven sheets of the positive electrode packed plate were housed in each bag-shaped separator A, and the bag-shaped separator containing the positive electrode packed plate and the negative electrode packed plate were alternately stacked to obtain a stack having seven sheets of the positive electrode packed plate and eight sheets of the negative electrode packed plate. As a result, in the stack, the positive electrode packed plate is arranged between the ribs formed on the inner surface of the bag-shaped separator. In addition, six identical stacks (stacks using the bag-shaped separator A) were produced.

[0033] For battery No. 2, six laminates using the bag-shaped separator B were produced in the same manner as for battery No. 1, except that seven sheets of the bag-shaped separator B were used. For battery No. 3, six laminates using the bag-shaped separator C were produced in the same manner as for battery No. 1, except that seven sheets of the bag-shaped separator C were used. For battery No. 4, six laminates using the bag-shaped separator D were produced in the same manner as for battery No. 1, except that seven sheets of the bag-shaped separator D were used. For battery No. 5, six laminates using the bag-shaped separator E were produced in the same manner as for battery No. 1, except that seven sheets of the bag-shaped separator E were used. For battery No. 6, six laminates using the bag-shaped separator F were produced in the same manner as for battery No. 1, except that seven sheets of the bag-shaped separator F were used.

[0034] Next, using a COS (cast-on-strap) casting device, straps, intermediate poles, and terminal poles were formed on the positive and negative electrode packing plates of the six stacks, respectively, to obtain six electrode plate groups. Next, the six electrode plate groups obtained were placed in six cell chambers of a monoblock-type battery case made of polypropylene. The protruding dimension of the guide rib on the inner wall of the battery case was adjusted so that the compression force in each cell chamber of the stack was constant within the range of 5 kPa to 10 kPa.

[0035] After that, the intermediate poles between adjacent cell chambers were resistance-welded and the battery case and lid were heat-welded in the usual manner. Next, aluminum sulfate was added to dilute sulfuric acid with a specific gravity of 1.230 to obtain an electrolyte with an aluminum ion concentration of 0.1 mol / L (specific gravity of 1.240), and this electrolyte was injected into each cell chamber through each injection hole in the lid. Next, the injection holes were sealed to assemble an unformed flooded lead-acid battery, and then the battery case was formed in the usual manner to turn the positive and negative electrode filled plates into positive and negative plates.

[0036] In this manner, two flooded lead-acid batteries No. 1 to No. 6 were obtained. For battery No. 7, eight pouch-shaped separators G were used, eight negative electrode packed plates were housed in each pouch-shaped separator G, and the pouch-shaped separators containing the negative electrode packed plates and the positive electrode packed plates were alternately stacked to obtain a stack having seven positive electrode packed plates and eight negative electrode packed plates. As a result, in the stack, the positive electrode packed plates were arranged between the ribs formed on the outer surface of the pouch-shaped separator. Six identical stacks (stacks using pouch-shaped separators G) were also produced.

[0037] For battery No. 8, six laminates were produced using bag-shaped separator I in the same manner as No. 7, except that eight sheets of bag-shaped separator I were used. For battery No. 9, six laminates were produced using bag-shaped separator J in the same manner as No. 7, except that eight sheets of bag-shaped separator J were used. For battery No. 10, six laminates were produced using bag-shaped separator K in the same manner as No. 7, except that eight sheets of bag-shaped separator K were used. Next, the steps subsequent to the preparation of the electrode plate assembly using each of the obtained laminates were carried out in the same manner as above, to obtain two flooded lead-acid batteries each of No. 7 to No. 10.

[0038] <Actual H and W measurements> One of the two resulting flooded lead-acid batteries No. 1 to No. 10 (fully charged state) was disassembled to measure the values ​​of H and W of the uneven portion 11 of the pouch-shaped separator 1. Specifically, first, the plate group was removed from the cell chamber (third cell chamber) two cells away from the cell chamber (first cell chamber) in which the plate group having the positive terminal pole was housed and disassembled, and the pouch-shaped separator that was located closest to the fourth cell chamber was removed.

[0039] Next, the uneven portion 11 of this bag-shaped separator was cut using a cutter so that the AA cross section in Fig. 1 was visible, and after cutting off half of the uneven portion 11 in the X direction and the flat portion 12, three measurement samples were taken from the remaining portion. That is, the uneven portion 11 and the portion continuous with the uneven portion 11 of the remaining portion were cut into small pieces of 10 mm (dimension in the Z direction) x 20 mm (dimension in the X direction) at positions where the length from the opening end in the Z direction was 1 / 4, 1 / 2, and 3 / 4 of the total, and three measurement samples were obtained.

[0040] Next, each measurement sample was embedded in epoxy resin, and the surface of the uneven portion 11 parallel to the AA cross section in Fig. 1 was exposed with a lab cutter, and this exposed surface was polished with five types of sandpaper (in the order of grit size 200, 400, 800, 1200, and 1500), and then buffed to a smooth mirror-like state. As a result, each measurement sample with a mirror-finished exposed surface was obtained. Next, the magnified image of the mirror-finished exposed surface of each measurement sample was taken with an optical microscope (HIROX RH-2000) to measure the H and W values, and the average H and W values ​​of the three measurement samples were calculated. The H / W ratio was then calculated using the average H and W values ​​obtained. As a result, it was confirmed that the values ​​in Table 1 were obtained.

[0041] In addition, it was visually confirmed that peeling had occurred at the uneven portion 11 in the pouch-shaped separator removed from the No. 1 flooded lead-acid battery, but no such peeling had occurred in the pouch-shaped separators removed from the No. 2 to No. 10 flooded lead-acid batteries.

[0042] [Evaluation test] The remaining one of the two resulting flooded lead-acid batteries No. 2 to No. 10 was not disassembled, but was used to carry out a charging test, and the change in the electrolyte level (height) before and after the test was examined. Specifically, a constant voltage and constant current charge was performed for 24 hours under the test conditions of the light load life test specified in "JIS D5301:2019 Starting Flooded Lead-Acid Batteries." Since the 20-hour rate capacity of No. 1 to No. 10 flooded lead-acid batteries was 60 Ah, the voltage was 16 V and the inrush current was 15 A.

[0043] The electrolyte level was measured before and after the test, and the relative value of the electrolyte level after the test was calculated, assuming that the electrolyte level before the test was 100. The change in the electrolyte level before and after the test was calculated using the average value of the six cell chambers. Specifically, the liquid level (height) of each cell chamber was measured before and after the test by measuring the distance T from the top of each injection hole in the lid to the liquid level in each cell chamber, and then the average value T was calculated. a Calculate the value T a and the difference between the distance L from the top of each injection hole on the cover to the bottom of the container (LT a ) was calculated to obtain the liquid level positions of the electrolyte before and after the test.

[0044] The results, together with the structure of the laminate, are shown in Table 2. Note that if the relative value of the liquid level position after the test exceeds 106, it is considered that the "effect of suppressing the rise in the electrolyte level is poor," so the battery performance was judged as "x" when it exceeded 106, as well as "good" when it was 106 or less, and the battery performance was judged as "◎" when the relative value of the liquid level position after the test was 104 or less, as it was considered that the "effect of suppressing the rise in the electrolyte level is particularly good," so the battery performance was judged as "◎."

[0045] [Table 2]

[0046] As shown in Table 2, among the No. 1 to No. 6 flooded lead-acid batteries in which the positive plate is housed in a pouch-shaped separator, the No. 2 to No. 5 flooded lead-acid batteries which satisfy 0.2≦H / W≦0.5 have excellent sealing performance of the pouch-shaped separator and suppress the rise in the electrolyte level, whereas the No. 6 flooded lead-acid battery with H / W=0.6 has no problem with the sealing performance of the pouch-shaped separator but is insufficient in suppressing the rise in the electrolyte level. Also, among the No. 2 to No. 5 flooded lead-acid batteries, the No. 2 to No. 4 flooded lead-acid batteries which satisfy 0.2≦H / W≦0.4 have particularly good suppression of the rise in the electrolyte level.

[0047] In addition, the flooded lead-acid batteries No. 7 to No. 10, in which the negative electrode plate was housed in a bag-shaped separator, satisfied 0.2≦H / W≦0.5, and had excellent sealing performance of the bag-shaped separator and suppressed rise in the electrolyte level. In addition, when comparing Nos. 2 and 7, Nos. 3 and 8, Nos. 4 and 9, and Nos. 5 and 10, which have the same hardware but different plates (first plates) housed in the bag-shaped separator, it was found that the flooded lead-acid batteries Nos. 2 to 5, in which the positive plate is housed in a bag-shaped separator, had a greater effect in suppressing the rise in the electrolyte level than the flooded lead-acid batteries Nos. 7 to 10, in which the negative plate is housed in a bag-shaped separator. [Explanation of symbols]

[0048] 1. Bag-shaped separator 11 Concave and convex part of the bag-shaped separator 12 Flat part of the bag-shaped separator 15 Bent end of bag-shaped separator 2 Positive plate 21 Grid portion of positive electrode plate 22 Positive electrode plate lug 3 Negative plate 4 Battery case 40 Cell Room 41 Battery case side panel 41a Inner surface of side panel 42 Battery case partition plate 42a Inner surface of partition plate 10 Laminate

Claims

1. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, an electrolyte injected into the cell chamber, and a lid fixed to the battery case and closing an upper portion of the cell chamber, the electrode plate group has a laminate including a plurality of positive electrode plates, a negative electrode plate, and a bag-shaped separator made of a synthetic resin; In the laminate, a first electrode plate, which is one of the positive electrode plate and the negative electrode plate, is housed in the bag-shaped separator, the bag-shaped separator containing the first electrode plate and a second electrode plate, which is the other of the positive electrode plate and the negative electrode plate, are alternately stacked, and a separator is disposed between the positive electrode plate and the negative electrode plate, The laminate is placed in the battery case with the plate surfaces of the positive electrode plate and the negative electrode plate aligned in the up-down direction of the battery case, the bag-shaped separator is open only at an upper side of the cell chamber, and both ends in a width direction, which is a direction perpendicular to the stacking direction and the up-down direction of the laminate, are closed by corrugated concave-convex portions that are continuous in the up-down direction and displaced in the stacking direction, and has a flat portion on the outer side of the concave-convex portions in the width direction, A flooded lead-acid battery in which the height difference (H) of the concave-convex portion and the repeating unit length (wavelength: W) satisfy the following formulas (1) to (3). 0.5mm≦H≦1.0mm...(1) 1.5mm≦W≦5.0mm...(2) 0.2≦H / W≦0.5 (3)

2. 2. The flooded lead-acid battery according to claim 1, wherein a height difference (H) of the concave-convex portion and a repeating unit length (W) satisfy the following formula (4): 0.2≦H / W≦0.4 (4)

3. 3. The flooded lead-acid battery according to claim 1, wherein the first plate is a positive plate.

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